Step 1

Bring a large pot of salted water to a boil and prepare an ice bath. Add green beans to boiling water and cook until tender-crisp, about 3 minutes. Transfer to ice bath using a wire mesh spider or tongs. Allow to chill completely, then drain and dry thoroughly with kitchen towels or paper towels.

Step 2

In a medium skillet, heat butter and almonds over medium-low heat and cook, stirring frequently, until almonds are deeply browned and nutty, about 5 minutes. Add garlic and shallot and cook, stirring, until lightly browned, about 2 minutes longer. Add lemon juice, along with a tablespoon or two of water. Increase heat to high and stir and shake pan rapidly to emulsify, about 30 seconds. The sauce should have a glossy sheen and not appear watery or greasy. If it's still watery, continue to simmer and shake. If it looks greasy, add another tablespoon of water to re-emulsify. When sauce is ready, remove from heat and season to taste with salt and pepper.

Step 3

Add beans to pan with sauce and toss to coat and combine. Return to medium heat and cook, tossing, until heated through, about 1 minute. Serve immediately.